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Old 13-10-2017, 01:38   #16
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Re: Perkins 4108 pushrod

On second thought, broken push rods could also be caused by rocker arms seizing on the rocker shaft, which will be obvious by just pulling the rocker shaft and respective arms and looking.


Unfortunately, fixing the root cause (insufficient oiling) is the same as for galled valves...though if this is the case, you might buy a little time by going up to 20W-50 oil and a friction modifier (I had a friend who used 90w gear oil in his nitro Harley race engines for a while...)
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Old 13-10-2017, 02:33   #17
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Re: Perkins 4108 pushrod

Running dirty oil too long will cause a buildup in smaller oil passages like the one going to the rocker shaft. Even though the gauge shows ok pressure, the head may not have had proper flow. The ends of the rocker shaft would have received the least flow or no flow.
Truckers often have flow problems in the heads if they stretch out oil changes. Sometimes there's so much damage a new head is cheaper than fixing. Unless you're using additional filtering the soot buildup in the oil will plug things up. Also running the engine for short periods (like over the winter) and never fully heating the oil can cause buildups.
It wasn't safe to run an engine with an unknown valve problem. The possible damage could have made the engine unrepairable.
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Old 13-10-2017, 03:55   #18
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Re: Perkins 4108 pushrod

Thank you gentlemen for the thoughtful replies. Unfortunately I don't know the hours on engine. The boat was acquired some years ago after being left in a marina for some time. I have always felt lucky that the motor even started let alone ran for all this time. Under my watch I have always tried to treat it well, twice yearly oil changes, clean fuel, making sure that it was up to temp every time it was started etc.
Oh well, she never left me stranded and this episode has all happened at the dock so I guess my luck is still holding. I would rather be sailing though.
Time to put the boat on the hard anyway to take care of bottom paint and other regular chores so just have to put pulling the engine into the mix.
As to doing the rebuild myself, I would say that I am a competent novice. Probably should stress novice as you can see from my haste it reinstalling the rods.
I think that I could probably follow the manual well enough to do the work but think the nuances might escape me. (Without your comments about oil flow I could easily overlook issues with the pump relief valve etc for example ) That being said, would you have any estimate of how many hours I might be looking at to complete the task. I have been doing some quick shopping around by phone and Internet as to costs of rebuild kits, having local mechanics do the job and buying an already rebuilt from somewhere like Foley.
Time is money I know but having the boat in the water instead of tying it to the ground is worth something too.
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Old 13-10-2017, 05:58   #19
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Re: Perkins 4108 pushrod

After reading several reviews probably not foley.
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Old 13-10-2017, 06:41   #20
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Re: Perkins 4108 pushrod

Seems a wise choice about Foley.

Regarding time to complete, it all depends.

Some points to consider;

If you rebuild your engine, you have a reasonable idea of 'where it's been'.

What are you plans? I 'rebuild' motors all the time, with a minimum of fuss; if the engine was running ok before, and the major parts look good; hone the cylinders, replace bearings, rings, oil pump, timing components, gaskets and seals, lap the valves with a cordless drill, and generally good for over another 100000 miles.

But one can always walk home...

Still, there are ways to do a completely adequate job without resorting to 'extraordinary measures'.

Since you're in there, besides getting all the basic engine up to snuff, if it's affordable now, a list of things ancillary to the engine to replace.

engine mounts
transmission drive plate
exhaust hoses
fuel lines
shaft packing
belts

The wiring should all be checked and repaired/renewed as necessary.

Now is also the time to consider adding or modifying any systems that can be improved to make maintenance easier.

The engine will have to be aligned after reinstallation.

All these things add up, so an hourly estimate would be wildly inaccurate.

Pulling numbers from you-know-where, given the old boy 3rds rule of estimating, 3000.00 for material+3000 for labor+3000 profit = 9000.00.

You can save a lot by doing it yourself, but as you say, 'time is money'.
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Old 26-11-2017, 15:22   #21
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Re: Perkins 4108 pushrod

Motor pulled from boat yesterday. Had to build an A-frame to get it out of the bilge and move it to the cockpit doorway so that the crane could snatch it out. Every thing seemed to have less than an inch of clearance, but slow and cautious got it done. Once I could get it out and get a better look I believe it's a 4107 instead of a 4108. One more thing that I thought I knew but was wrong about.
"Open heart surgery" should start next week and I will know what happened. Looking forward to making a few upgrades and cleaning up fuel lines and bilge, etc.
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Old 28-11-2017, 15:49   #22
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Re: Perkins 4108 pushrod

A 4-107 has 4 evenly spaced approximately 1/8 inch diameter holes on the port side of the block. They communicate with the lower cylinder liner seals. If they show signs of weeping or corrosion the liners should probably be pulled and the seals renewed in addition to whatever else turns up.

I found myself in a similar position and replaced the engine with a rebuilt 4-108. I later replaced that with a Beta 50. It was basically a drop in. If I were you I would really think about the Beta as an option. The 4-107 and 108 are getting "pretty long in the tooth"!

All above IMHO:-)
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